Chemical Physics Letters, Vol.430, No.4-6, 227-234, 2006
The 1(2)B(1), 1(2)B(2) 1(2)A(1), 1(2)A(2), 3(2)A'(2(2)B(2)) and 2(2)A(1) states of the 1,1-difluoromethane ion studied using multiconfiguration second-order perturbation theory
The 1(2)B(1)((XB1)-B-2), 1(2)B(2), 1(2)A(1), 1(2)A(2), 2(2)B(2), and 2(2)A(1) states of the CH2F2+ ion were studied using CASPT2 and CASSCF methods. Calculations suggest that one should consider the 3(2)A' state instead of 2(2)B(2). The CASPT2 T-0 calculations predict the energy ordering of 1(2)B(1)((XB1)-B-2), 1(2)B(2), 1(2)A(1), 1(2)A(2), 3(2)A', and 2(2)A(1), which is in line with the experimental results by Pradeep and Shirley. The CASPT2 T-0 values for the 1(2)B(2), 1(2)A(2), 3(2)A', and 2(2)A(1) states are close to the experimental values. The F-loss and H-loss dissociation processes were studied at the CASPT2//CASSCF level. The energy levels of low-lying states of CH2F2+ and CH2Cl2+ are compared. (c) 2006 Elsevier B.V. All rights reserved.